Automatic de-icing system



Dec. 16, 1958 A. c. VELDHUIS 2,864,927

AUTOMATIC DE-ICING SYSTEM Original Filed. Sept. 29. 1953 Know-#54575 Wamw BY 43M 47, M

ATTORNEY United States PatentOi AUTOMATIC DE-ICING SYSTEM 2"Claims. (Cl. 215-19 Thisinvention relates to a system which responds automatically to ice forming conditions and applies power to,a de-icing circuit so long as the ice forming conditi'ons continue.

This application is a division of my'co-pending appli cation Serial No. 383,112, filed Patent No. 2,786,927.

My invention is also concerned with a novel form of ice collector for detecting ice forming conditions.

' The system of my invention involves an icing condition detector controlling an automatic de-icing system to prevent the formation of ice on .outdoor structures, such as wind power plants, radio antenna installations, power transmission lines, towers in general, and bridges.

My invention is illustrated in the accompanying drawing in which Figure 1 is a diagrammatic representation of one form of icing condition detector and indicator employing a counterbalanced wire grid as the ice collector; t

'Figure 2 is a'front view of the wire grid of Figure 1;

Figure 3 is a diagrammatic view of the complete deicing system and showing a different form of icing condition detector from that shown in Figures 1 and 2; and

Figure 4 shows another form of ice collector suitable for use in Figure 3.

Referring to Figure 1, 1 indicates the top portion of a suitable tower. for supporting the ice formation detector. Certain parts of the detectorare enclosed with- September 29, 1953, now

' in a suitably streamlined casing 2 mounted upon the tower 1 for turning about a vertical axis. A balance beam or bar 3 is arranged so that one end thereof extendsinto the casing 2 from the front of the casing and is suitably mounted for pivotal swinging about horizontal axis 4. The balance bar 3 may be formed of a hollow tube. The front end of casing 2 is sealed around bar 3 by suitable means, such as a flexible diaphragm, to prevent the entry of moisture into the casing. An ice collector in the form of a metal wire grid 5 is mounted at the front end of the bar 3, the plane of the grid being arranged at right angles to the axis of the bar 3, and one end'of the grid being connected to the bar by wire section 5a and the other end of the grid being connected by wire section 5b to an insulating conductor passing through the arm 3 and into the casing 2. A suitable tail or wind-vane 6 is attached to the casing 2 and extends rearwardly therefrom for the purpose of keeping the grid 5 facing into the wind.

Within the casing 2 suitable biasing means represented by the spring 7 is provided to normally hold the bar 3 against a fixed stop represented at 8. The biasing force is sufiicient only to counterbalance the weight of the bar 3 and the collector 5 when these elements are free of ice, but formation of ice on these elements causes the bar 3 to tilt in an anti-clockwise direction about the axis 4 against the action of the biasing spring 7. An electric switch 9 enclosed in the housing 2 is arranged to be controlled by the bar 3 so that with the bar in its normal position and resting against the stop .8 the switch is g 2,864,927 Patented Dec. 16, 1958 under the weight of ice formed on the grid 5. The switch 9] is connected to control the primary circuit of a step-.

down transformer 10 arranged in the casing 2, the secondary winding of which is connected to supply heating current through the metal wire grid 5 by way of insulated conductor 50. Transformer 10 is energized from a suitable source of alternating current represented at 11, and this source may be a commercial power circuit, or itmay be supplied from a local source such as a wind driven generator. The switch 9 also controls the energization of a suitable indicator, and in the example shown in Figure 1 the indicator assumes the form of an electric lamp 12 connected in the energizing circuit of the transformer 10, but a separate energizing circuit for the lamp 12 may be provided if desired. It will be understood that the lamp 12 will usually be located at some place remote from the tower 1.

The operation of Figure l is as follows:

So long as the weather conditions are dry and above freezing temperature, the exposed part of the bar 3 and the grid Swill be free of ice, and the switch 9 will be held in open position. As soon as ice forms on the grid 5 sufiicient to cause closing of the switch 9, heating current will be supplied to the grid 5 through the trans is energized intermittently, that is, during the intervals when ice depresses the grid 5, it is possible, by the arfor limited vertical movement.

rangement shown inFigure 3, to produce continuous energ'ization of the lamp 12 so long as icing conditions;

exist.

'In the arrangement shown in Figure 3, a different form of ice collector is employed which permits considerable simplification in the arrangementv The preferred form of-casing in this arrangement is cylindrical in shape as shown at 2' and is mounted in fixed position at the top of any suitable support, not shown. The ice collector in this arrangement is in the form of a conical member 13 mounted above the casing 2, and preferably in axial alignment with the casing. The cone 13 is supported upon a tubular stem" 13a which extends downwardly into the casing 2' and is supported in suitable bearings, not shown, The weight of the cone 13 and of the parts moving therewith is normally counterbalanced by suitable biasing means, such as the springs 14 arranged within the casing 2 and connected between an upper part of the casing 2' and a cross-member 15 secured to the lower end of the stem 13a. An'electric switch having two contacts 9a and 9b is arranged within the housing 2 and is controlled by the member 15 so that the contacts are normally open when the collector 13 is free of ice and is held in its upper position, but the contacts are moved to the closed position when the collector 13 is depressed under the weight of ice formed thereon.

A heater wire 16 is carried by conical member 13, preferably in the form of a conical spiral, the lower end of the spiral being connected to the vertical tube or stem 13:: and thence through various conducting parts to the metallic casing 2. The upper end of the heater spiral 16 is connected to an insulating conductor passing through the stem 13a and being connected to one terminal of the secondary winding of transformer 10, the other terminal of the secondary winding being grounded to the casing 2'. Wire 16 may be secured to the outer surface of cone 13, but it is preferred to embed the wire in the wall of the cone. Switch contact 9a controls the energizing circuit of transformer 10 in the manner indicated above for Figure V 1.. Switch contact 9b controls a separate. circuit which energizes a relay 17 and a suitable recording device 18 for making a record of the'operation of the icing conditions. Relay 17 controls a circuit whichenergizes a signal lamp 12 and suitable 'de icing c'ircuit 19. Relay 17 is of the type which closes instantly but is slow to release. This relay is designed so that its contacts remain closed after each operation for a period of time greater than the time which the contact 9b of the ice detector switch is open during its normal cycle of operation. With this arrangement, so long as icing conditions exist, the icing detector will function in repeated cycles to open and close the switch 9b, but the relay 17 will remain closed, and the indicator lamp 12 and thede icing circuit 19 will be energized continuously so long as icing conditions exist. As soon as the icing conditions disappear and the contact 9b remains open for a time longer than the release time for relay 17, the lamp 12 and the de-icing circuit 19 will be de-energized.

It will be understood that the de-icing circuit 19 will be arranged to apply heat to any desired structure or location, such as those mentioned in the first part of this specification.

In Figure 4 I have illustrated a modified form of ice collector which may be used in the arrangement shown in Figure 3. In this arrangement the collector 13 is in the form of a conical element as in Figure 3, but instead of using a spiral wire heater. on the collector, the heating element is formed of a thin metallic film applied to the conical surface of collector 13 and connected at the lower edge with a ring 13b of low resistance and the upper part of the film is connected to a cap 13c of low resistance. One

, terminal of the secondary winding of transformer would be connected to the cap member 13c by an insulating conductor passing through the stem 13a, and the other terminal of the secondary winding would be connected through various conducting parts to the ring 13b. I The heater film may form the outer surface of the cone 13, but it is preferred to cover the metallic film with a protective layer of varnish.

In the ice-collectors shown in Figures 3 and 4, the icecollecting area is formed symmetrically about the vertical axis so that its wind resistance and ice-collecting function is independent of the wind direction, and it is not necessary to mount the collector element for turning about the vertical axis.

1 claim:

1. An automatic de-icing system comprising a de-icing circuit,a source of electric power, a slow-release electromagnetic relay for connecting said de-icing circuit to said element to melt ice therefrom, means controlled by said' collector element in its lower position for energizing said heating means, whereby said collector element is oscillated periodically between said upper and lower positions in response to continued ice forming conditions, and a control switch actuated by the periodic movement of said ice collector element vfor periodically energizing said relay during intervals when said collector element is in the lower position, the release time of said relay being greater than the interval during each cycle of operation of said collector element when said control switch is open.

2. An icing condition indicator comprising an ice-collector element mounted to move from an upper position to a lower position underthe weight of ice collected thereon, biasing means counterbalancing the weight of said collector element and normally holding said collector element in its upper position, said collector element com-g prising a member presenting a conical ice-collecting surface formed symmetrically about a vertical axis and pre senting uniform wind-resistance and ice-collecting capacity in all directions about said axis, heating means carried by said collector element to melt ice therefrom and comprising an electrical resistance distributed over the entire ice-collecting area of said collector, a source of electric current for energizing said resistive heating means, and.

switch means controlled by said collector element in its lower positionfor connecting said source to said heating means, whereby said collector element oscillates periodically between said upper and lower positions in response to continued ice-forming conditions.

References Cited in the file of this patent UNITED STATES PATENTS 2,159,186 Tyler May 23, 1939' 2,566,813 Thorsen Sept. 4, 1951 2,662,156 Potter Dec. 8, 1953 2,699,303 Chilman Jan. 11, 1955 2,786,927

embodying means for main- Veldhuis Mar. 26, 1957". 

